In electronics field, especially in the field of liquid crystal panel manufacture, it is often necessary to convey for example a glass substrate between devices intended for different processes. During the conveyance of the glass substrate, it is easy to occur the substrate deviates the correct placement position, so the position of the substrate, especially whether the substrate is aligned, needs to be detected. In order to detect whether the substrate is aligned, it is particularly necessary to detect the position and the orientation of its edge. An existing position detection device usually has separate parts, for example a emitter and a receiver separated from each other (as shown in FIG. 1). The detection device detects based on signals given by a single emitter and a single receiver whether a substrate located therebetween is aligned. The detection device has a fixed position, which makes it difficult to carry out real-time measurement during the conveyance with satisfactory accuracy.
In addition, upon detection of deviation of the position of the substrate during the conveyance, the position of the substrate is often corrected through rigid adjustment of a device center position, which will easily result in damage to the substrate.